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  • Y. Jiang, J. A. Madsen, V. Farutin, J. C. Lansing, et R. B. Cole, « High fidelity approach for proteomic scale enrichment and identification of N-termini », International Journal of Mass Spectrometry, vol. 391, p. 115-122, nov. 2015.
    Résumé : A novel workflow was designed for the large-scale identification of protein N-terminal sequences. The workflow started with converting lysine to homoarginine, followed by reaction with sulfonation of N-termini by 4-sulfophenyl isothiocyanate (SPITC). Upon trypsin digestion, the SPITC modified N-terminal peptides were enriched by electrostatic repulsion hydrophilic interaction (ERLIC) chromatography in which the internal and C-terminal peptides eluted at the void volume, and the SPITC peptides were retained in the column due to the hydrophilicity and electrostatic attraction of the sulfonyl group to the stationary phase. Upon higher-energy collisional induced dissociation (HCD) SPITC peptides in ESI generated predominately y-type ion series; such simplification of spectra enables the identification of N-termini with high confidence. The appearance of b1 + SPITC product ions upon HCD further boosts the confidence for N-terminal identifications. This method was applied to an Escherichia coli cell lysate, thus allowing the identification of 358 high confidence N-terminal peptides representing 274 distinct E. coli proteins as certain proteins were found to have multiple N-terminal peptides due to cleavage from various cellular enzymes. Confidence in N-terminal assignments is further heightened since 224 of the unique proteins identified from N-terminal peptides were also identified in the analysis of flow-through fractions.
    Mots-clés : CSOB, ERLIC enrichment, N-termini proteomics, POLE 3, SPITC modification.

  • D. Lesage, G. Barozzino-Consiglio, R. Duwald, C. Fressigné, A. Harrison-Marchand, K. F. Faull, J. Maddaluno, et Y. Gimbert, « A Lithium Amide Protected Against Protonation in the Gas Phase: Unexpected Effect of LiCl », The Journal of Organic Chemistry, vol. 80, nᵒ 12, p. 6441-6446.
    Résumé : In cold THF and in the presence of LiCl, a lithium pyrrolidinylamide forms a 1:1 mixed aggregate, which is observed directly by ESI-MS. Gas-phase protonation of this species leads to selective transfer of H+ to the chlorine, suggesting that LiCl shields the amide nitrogen and prevents its direct protonation.
    Mots-clés : CSOB, POLE 3.

  • J. - P. Mbakidi, F. Brégier, T. - S. Ouk, R. Granet, S. Alves, E. Rivière, S. Chevreux, G. Lemercier, et V. Sol, « Magnetic Dextran Nanoparticles That Bear Hydrophilic Porphyrin Derivatives: Bimodal Agents for Potential Application in Photodynamic Therapy », ChemPlusChem, vol. 80, nᵒ 9, p. 1416-1426.
    Résumé : This study reports the chemical synthesis of a class of dextran superparamagnetic nanoparticles that bear hydrophilic porphyrin units covalently grafted by a click chemistry reaction in aqueous solution. Magnetic nanoparticles are used in magnetic resonance imaging (MRI) and hyperthermia, and the grafting of hydrophilic photosensitizers (PS) leads to elaborate new multifunctional platforms for potential diagnostic and targeted photodynamic therapy (PDT). The therapeutic potential for PDT of these nanoparticles is evaluated in vitro against the HaCaT cell line. The results show that these new multicharged nanomagnets—in particular, those that bear cationic porphyrins—show a significant uptake and an interesting photocytotoxic activity toward HaCaT cells. The whole series of these synthesized PS are massively incorporated inside HaCat cells and associated with mitochondria.
    Mots-clés : click chemistry, CSOB, Magnetic properties, nanoparticles, photodynamic therapy, POLE 3, porphyrinoids.

  • M. Pérot-Taillandier, C. Afonso, Q. Enjalbert, R. Antoine, P. Dugourd, R. B. Cole, J. - C. Tabet, S. Rebuffat, et S. Zirah, « Electron detachment/photodetachment dissociation of lasso peptides », International Journal of Mass Spectrometry, vol. 390, p. 91-100.
    Résumé : Lasso peptides are bioactive peptides produced by bacteria, characterized by a mechanically interlocked topology where the C-terminal tail of the peptide is threaded through and trapped within an N-terminal macrolactam ring. The structural characterization of lasso peptides and differentiation from their unthreaded topoisomers by mass spectrometry are challenging tasks. We previously explored the fragmentation mechanisms of lasso peptides in positive ion mode and showed several signatures of the lasso topology under collision induced dissociation (CID) and electron capture dissociation. Here we analyzed the dissociation of the multiply-deprotonated microcin J25 (MccJ25), a 21-residue lasso peptide produced by Escherichia coli, together with its non-lasso topoisomer and several variants generated by site-directed mutagenesis, under different modes of activation. The fragmentation patterns obtained by CID for the threaded and unthreaded structures were very similar. By contrast, electron detachment dissociation (EDD) as well as activated-electron photodetachment dissociation (a-EPD) revealed very different dissociation pathways for the two topoisomers. The doubly deprotonated topoisomers showed a different deprotonation pattern, Tyr20 residue being deprotonated for MccJ25 only, yielding the singly charged [c19−C2H4O] product ion. MccJ25 also triggered several two-peptide product ions diagnostic of the lasso topology, including the [(c8)*(z2)] species, which could be maintained by either a covalent or a non-covalent linkage.
    Mots-clés : CSOB, Electron detachment dissociation, Electron photodetachment dissociation, Lasso peptides, POLE 3.

  • B. P. Pozniak et R. B. Cole, « Perspective on Electrospray Ionization and Its Relation to Electrochemistry », Journal of The American Society for Mass Spectrometry, vol. 26, nᵒ 3, p. 369-385.
    Résumé : The phenomenon of electrospraying of liquids is presented from the perspective of the electrochemistry involved. Basics of current and liquid flow in the capillary and spray tip are discussed, followed by specifics of charging and discharging of the sprayed liquid surface. Fundamental theories and numerical modeling relating electrospray current to solution and spray parameters are described and then compared with our own experimentally obtained data. The method of mapping potentials and currents inside the electrospray capillary by using an inserted electrically-isolated small wire probe electrode is discussed in detail with illustrations from new and published data. Based on these experimentally obtained results, a new mathematical model is derived. The introduced “nonlinear resistor electrospray capillary model” divides the electrospray capillary into small sections, adds their contributions, and then, by transition to infinitely small section thickness, produces analytical formulas that relate current and potential maps to other properties of the electrospraying liquid: primarily conductivity and current density. The presentation of the model is undertaken from an elementary standpoint, and it offers the possibility to obtain quantitative information regarding operating parameters from typical analytical systems subjected to electrospray. The model stresses simplicity and ease of use; examples applying experimental data are shown and some predictions of the model are also presented. The developed nonlinear resistor electrospray capillary model is intended to provide a new quantitative basis for improving the understanding of electrochemical transformations occurring in the electrospray emitter. A supplemental material section gives full derivation of the model and discusses other consequences.Graphical Abstractᅟ
    Mots-clés : CSOB, POLE 3.

  • B. Quéméner, J. Vigouroux, E. Rathahao, J. C. Tabet, A. Dimitrijevic, et M. Lahaye, « Negative electrospray ionization mass spectrometry: a method for sequencing and determining linkage position in oligosaccharides from branched hemicelluloses », Journal of Mass Spectrometry, vol. 50, nᵒ 1, p. 247-264.
    Résumé : Xyloglucans of apple, tomato, bilberry and tamarind were hydrolyzed by commercial endo β-1-4-D-endoglucanase. The xylo-gluco-oligosaccharides (XylGos) released were separated on CarboPac PA 200 column in less than 15 min, and, after purification, they were structurally characterized by negative electrospray ionization mass spectrometry using a quadrupole time-of-flight (ESI-Q-TOF), a hybrid linear ion trap (LTQ)/Orbitrap and a hybrid quadrupole Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers. In order to corroborate the fragmentation routes observed on XylGos, some commercial galacto-manno-oligosaccharides (GalMOs) and glucurono-xylo-oligosaccharides were also studied. The fragmentation pathways of the ionized GalMos were similar to those of XylGos ones. The product ion spectra were mainly characterized by prominent double cleavage (D) ions corresponding to the entire inner side chains. The directed fragmentation from the reducing end to the other end was observed for the main glycosylated backbone but also for the side-chains, allowing their complete sequencing. Relevant cross-ring cleavage ions from 0,2Xj -type revealed to be diagnostic of the 1-2-linked- glycosyl units from XylGos together with the 1-2-linked glucuronic acid unit from glucuronoxylans. Resonant activation in the LTQ Orbitrap allowed not only determining the type of all linkages but also the O-acetyl group location on fucosylated side-chains. Moreover, the fragmentation of the different side chains using the MSn capabilities of the LTQ/Orbitrap analyzer also allowed differentiating terminal arabinosyl and xylosyl substituents inside S and U side-chains of XylGos, respectively. The CID spectra obtained were very informative for distinction of isomeric structures differing only in their substitution pattern. These features together makes the fragmentation in negative ionization mode a relevant and powerful technique useful to highlight the subtle structural changes generally observed during the development of plant organs such as during fruit ripening and for the screening of cell wall mutants with altered hemicellulose structure. Copyright © 2015 John Wiley & Sons, Ltd.
    Mots-clés : CSOB, endo β-1-4 endoglucanase, hemicellulose, HPAEC, negative ESI-MS, POLE 3, xyloglucans.

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    S. Schramm, D. Léonço, C. Hubert, J. - C. Tabet, et M. Bridoux, « Development and validation of an isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry method for the reliable quantification of 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) and 14 other explosives and their degradation products in environmental water samples », Talanta, vol. 143, p. 271-278.
    Résumé : A comprehensive method for the determination and characterization of 15 common explosive compounds in water samples by ultra-high pressure liquid chromatography–atmospheric pressure chemical ionization-tandem mass spectrometry (APCI-MS/MS) is presented. The method allows the determination of 10 nitroaromatics, two nitroamines and three nitrate ester compounds. Among these, 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) was quantified and detected for the first time in our knowledge at trace levels (0.2 µg/L). Furthermore, the collision induced dissociation (CID) mass spectrum of TATB is discussed and a fragmentation mechanism is proposed. The signal for each explosive was normalized by isotopically-enriched congeners used as internal standards. The limits of detection (LOD) reached 20 ng/L, depending on the type of energetic molecule, which are adequate for water samples and the linearity was verified from 1.4 to 2 orders of magnitude. The sensitivity of the UHPLC–APCI-MS/MS approach allows direct injection of aqueous samples without preceding extraction for concentration. Besides, the method displays a good reliability with low signal suppression in various matrices such as spring water, mineral water, acidified water or ground water. The effectiveness of the method is demonstrated by the analysis of underground water samples containing traces of explosives from test fields in France.
    Mots-clés : Chromatography, CSOB, Explosive, mass spectrometry, Nitroaromatic compounds, POLE 3, TATB.

  • A. Schwarzenberg, J. - C. Tabet, R. B. Cole, X. Machuron-Mandard, et H. Dossmann, « New insights into dissociation of deprotonated 2,4-dinitrotoluene by combined high-resolution mass spectrometry and density functional theory calculations », Rapid Communications in Mass Spectrometry, vol. 29, nᵒ 1, p. 29-34.
    Résumé : RATIONALE 2,4-Dinitrotoluene (2,4-DNT) is a nitroaromatic explosive which is commonly found in environmental samples close to training points, firing places, and manufacturers. Mass spectrometry analysis of this compound shows one main product ion that distinguishes it from the other isomers of DNT. We present here a detailed mechanistic study on the formation of this ion. METHODS 2,4-DNT was analyzed using negative electrospray ionization high-resolution mass spectrometry (ESI-HRMS) using a linear ion trap quadrupole LTQ-Orbitrap XL mass spectrometer. Collision-induced dissociation (CID) experiments were performed on the [M–H]– ion obtained. Density functional theory (DFT) calculations were used to support experimental observations. RESULTS Fragmentation of deprotonated 2,4-DNT [M–H]– (m/z 181) yields a main product ion at m/z 116. The mechanism of formation of this diagnostic product ion is not obvious and it has never been rationalized. Calculations were performed to probe different mechanistic variants, which are discussed in this work. CONCLUSIONS Analysis of possible pathways to form the m/z 116 ion from the m/z 181 precursor shows that its formation is likely to proceed first via NO• loss, followed by eliminations of H2O and then HO•. Copyright © 2014 John Wiley & Sons, Ltd.
    Mots-clés : CSOB, POLE 3.

  • J. Shraberg, S. W. Rick, N. Rannulu, et R. B. Cole, « A study of procyanidin binding to Histatin 5 using Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS) and molecular simulations », Physical Chemistry Chemical Physics, vol. 17, nᵒ 18, p. 12247-12258.
    Résumé : Tannins act as antioxidants, anticarcinogens, cardio-protectants, anti-inflammatory and anti-microbial agents and bind to salivary peptides by hydrophilic and hydrophobic mechanisms. Electrospray Ionization Mass Spectrometry (ESI-MS) has been used to assess both hydrophilic and hydrophobic components of noncovalent binding in protein complexes. In the present study, direct infusion Electrospray-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ES-FTICR MS) is used to assess relative binding affinities of procyanidin tannin stereoisomers for salivary peptides arising from aqueous solutions. The condensed tannins procyanidin B1, B2, B3, and B4 demonstrate significantly different binding affinities for the salivary peptide Histatin 5. Rigid docking combined with molecular dynamics optimization is used to investigate procyanidin–Histatin 5 binding mechanisms and as a basis to rationalize trends found in the corresponding ES-FTICR MS experiments. The relative binding affinities of the four procyanidin rotamers are different in the gas and liquid phases. The simulation results indicate that many of the same contact points are made in both phases, but there is a increase in strong electrostatic interactions and an decrease in π–π contacts upon transfer from the liquid to the gas phase. The simulations reveal that the tannin interactions can make close contacts with a variety of amino acid residues on the peptide.
    Mots-clés : CSOB, POLE 3.

  • V. P. Stankov-Jovanović, M. D. Ilić, V. D. Mitić, T. M. Mihajilov-Krstev, S. R. Simonović, S. D. Nikolić Mandić, J. C. Tabet, et R. B. Cole, « Secondary metabolites of Seseli rigidum: Chemical composition plus antioxidant, antimicrobial and cholinesterase inhibition activity », Journal of Pharmaceutical and Biomedical Analysis, vol. 111, p. 78-90.
    Résumé : Extracts of different polarity obtained from various plant parts (root, leaf, flower and fruit) of Seseli rigidum were studied by different antioxidant assays: DPPH and ABTS radical scavenging activity, by total reducing power method as well as via total content of flavonoids and polyphenols. Essential oils of all plant parts showed weak antioxidant characteristics. The inhibitory concentration range of the tested extracts, against bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and fungi Candida albicans and Aspergillus niger was 0.01–1.50 mg/mL and of a microbicidal 0.02–3.00 mg/mL. In the interaction with cholinesterase, all essential oils proved effective as inhibitors. The highest percentage of inhibition versus human and horse cholinesterase was shown by root essential oil (38.20% and 48.30%, respectively) among oils, and root hexane extract (40.56% and 50.65% respectively). Essential oils and volatile components of all plant parts were identified by GC, GC–MS and headspace/GC–MS. Statistical analysis of the ensemble of results showed that the root essential oil composition differed significantly from essential oils of other parts of the plant. Taking into account all of the studied activities, the root hexane extract showed the best overall properties. By means of high performance liquid chromatography coupled to high resolution mass spectrometry, the 30 most abundant constituents were identified in extracts of different polarity. The presence of identified constituents was linked to observed specific biological activities, thus designating compounds potentially responsible for each exhibited activity.
    Mots-clés : Antimicrobial activity, antioxidant activity, Cholinesterase inhibition, CSOB, POLE 3, Secondary metabolites, Seseli rigidum.

  • T. Tripković, C. Charvy, S. Alves, A. D. Lolić, R. M. Baosić, S. N. Nikolić-Mandic, et J. C. Tabet, « Electrospray ionization linear trap quadrupole Orbitrap in analysis of old tempera paintings: application to nineteenth-century Orthodox icons », European Journal of Mass Spectrometry, vol. 21, nᵒ 4, p. 679-692.

  • A. Warnet, N. Auzeil, et J. - C. Tabet, « Unusual Post-Spray Proton Transfer to Protein Using Acetone Spray in Desorption Electrospray Ionization », Journal of Analytical & Bioanalytical Techniques, vol. 6, nᵒ 6.
    Résumé : Although acetone, in DESI ionisation generally leads to protein aggregation, in this study we report unexpected multi-proton transfers to lysozyme using this aprotic solvent as a charged spray. The DESI/acetone mass spectrum of lysozyme displays (i) a significant increase in the average charge state (Zav) and (ii) an incomplete H+/Ca2+ exchange, even though the overall contribution of cationised species is high, relative to those from spraying with a methanol/water solvent. This behavior is contrary to that expected from gas phase basicity, because GBacetone >GBmethanol. Decreasing the amount of sample deposited on the target (from 50 to 0.050 pmole) leads to a charge state increase, as seen in ESI, but not in the extent of cationisation. Moreover, the DESI signal duration is extended with sprayed acetone even though the total ionic current is significantly lowered. With a d6-acetone spray, no incorporation of a deuteron occurs, and the ionization yield is strongly decreased for multi-protonated lysoi+ lysozyme. This is in contrast to that observed with a d4-methanol spray, which displays a distribution of 48 deuterons in the lyso9+ ion as shown in high resolution with a LTQ/Orbitrap instrument. This unexpected behavior of the (CD3)2CO spray suggests that protons do not originate from acetone. Furthermore, dry argon post-flow on the target surface results in the lysozyme signal suppression, whereas with a humid argon flow, the signal is regenerated. On the other hand, an argon stream bubbling in heavy water, yields incorporation of several deuterons. The interpretation of this behavior is explained by considering the acetone radical ions at the surface of the primary droplets (and/or offspring droplets and/or at the wet sample surface), being able to react with ambient moisture (or with traces of water adsorbed at liquid phase). Under these conditions, enough protons are produced to generate multi-charged solvated lysozyme aggregates which then become desolvated in the reduced pressure in the skimmer area.
    Mots-clés : CSOB, POLE 3.

  • Z. Zendong, P. McCarron, C. Herrenknecht, M. Sibat, Z. Amzil, R. B. Cole, et P. Hess, « High resolution mass spectrometry for quantitative analysis and untargeted screening of algal toxins in mussels and passive samplers », Journal of Chromatography A, vol. 1416, p. 10-21.
    Résumé : Measurement of marine algal toxins has traditionally focussed on shellfish monitoring while, over the last decade, passive sampling has been introduced as a complementary tool for exploratory studies. Since 2011, liquid chromatography–tandem mass spectrometry (LC–MS/MS) has been adopted as the EU reference method (No. 15/2011) for detection and quantitation of lipophilic toxins. Traditional LC–MS approaches have been based on low-resolution mass spectrometry (LRMS), however, advances in instrument platforms have led to a heightened interest in the use of high-resolution mass spectrometry (HRMS) for toxin detection. This work describes the use of HRMS in combination with passive sampling as a progressive approach to marine algal toxin surveys. Experiments focused on comparison of LRMS and HRMS for de

    termination of a broad range of toxins in shellfish and passive samplers. Matrix effects are an important issue to address in LC–MS; therefore, this phenomenon was evaluated for mussels (Mytilus galloprovincialis) and passive samplers using LRMS (triple quadrupole) and HRMS (quadrupole time-of-flight and Orbitrap) instruments. Matrix-matched calibration solutions containing okadaic acid and dinophysistoxins, pectenotoxin, azaspiracids, yessotoxins, domoic acid, pinnatoxins, gymnodimine A and 13-desmethyl spirolide C were prepared. Similar matrix effects were observed on all instruments types. Most notably, there was ion enhancement for pectenotoxins, okadaic acid/dinophysistoxins on one hand, and ion suppression for yessotoxins on the other. Interestingly, the ion selected for quantitation of PTX2 also influenced the magnitude of matrix effects, with the sodium adduct typically exhibiting less susceptibility to matrix effects than the ammonium adduct. As expected, mussel as a biological matrix, quantitatively produced significantly more matrix effects than passive sampler extracts, irrespective of toxin. Sample dilution was demonstrated as an effective measure to reduce matrix effects for all compounds, and was found to be particularly useful for the non-targeted approach. Limits of detection and method accuracy were comparable between the systems tested, demonstrating the applicability of HRMS as an effective tool for screening and quantitative analysis. HRMS offers the advantage of untargeted analysis, meaning that datasets can be retrospectively analyzed. HRMS (full scan) chromatograms of passive samplers yielded significantly less complex data sets than mussels, and were thus more easily screened for unknowns. Consequently, we recommend the use of HRMS in combination with passive sampling for studies investigating emerging or hitherto uncharacterized toxins.
    Mots-clés : CSOB, Marine toxins, Matrix effects, Monitoring, Passive sampling, POLE 3, SPATT.


  • S. Boudah, M. - F. Olivier, S. Aros-Calt, L. Oliveira, F. Fenaille, J. - C. Tabet, et C. Junot, « Annotation of the human serum metabolome by coupling three liquid chromatography methods to high-resolution mass spectrometry », Journal of Chromatography B-Analytical Technologies in the Biomedical and Life Sciences, vol. 966, p. 34-47.
    Résumé : This work aims at evaluating the relevance and versatility of liquid chromatography coupled to high resolution mass spectrometry (LC/HRMS) for performing a qualitative and comprehensive study of the human serum metabolome. To this end, three different chromatographic systems based on a reversed phase (RP), hydrophilic interaction chromatography (HILIC) and a pentafluorophenylpropyl (PFPP) stationary phase were used, with detection in both positive and negative electrospray modes. LC/HRMS platforms were first assessed for their ability to detect, retain and separate 657 metabolite standards representative of the chemical families occurring in biological fluids. More than 75% were efficiently retained in either one LC-condition and less than 5% were exclusively retained by the RP column. These three LC/HRMS systems were then evaluated for their coverage of serum metabolome. The combination of RP, HILIC and PFPP based LC/HRMS methods resulted in the annotation of about 1328 features in the negative ionization mode, and 1358 in the positive ionization mode on the basis of their accurate mass and precise retention time in at least one chromatographic condition. Less than 12% of these annotations were shared by the three LC systems, which highlights their complementarity. HILIC column ensured the greatest metabolome coverage in the negative ionization mode, whereas PFPP column was the most effective in the positive ionization mode. Altogether, 192 annotations were confirmed using our spectral database and 74 others by performing MS/MS experiments. This resulted in the formal or putative identification of 266 metabolites, among which 59 are reported for the first time in human serum. (C) 2014 Elsevier B.V. All rights reserved.
    Mots-clés : CSOB, database, extraction, fragmentation trees, high resolution mass spectrometry, identification, liquid chromatography, Metabolite identification, Metabolome annotation, metabolomics, ms, performance, phase stationary phases, POLE 3, reversed-phase, serum, strategy, Structure elucidation, Tandem mass spectrometry.

  • J. Cotton, F. Leroux, S. Broudin, M. Marie, B. Corman, J. - C. Tabet, C. Ducruix, et C. Junot, « High-Resolution Mass Spectrometry Associated with Data Mining Tools for the Detection of Pollutants and Chemical Characterization of Honey Samples », Journal of Agricultural and Food Chemistry, vol. 62, nᵒ 46, p. 11335-11345.
    Résumé : Analytical methods for food control are mainly focused on restricted lists of well-known contaminants. This paper shows that liquid chromatography high-resolution mass spectrometry (LC/ESI-HRMS) associated with the data mining tools developed for metabolomics can address this issue by enabling (i) targeted analyses of pollutants, (ii) detection of untargeted and unknown xenobiotics, and (iii) detection of metabolites useful for the characterization of food matrices. A proof-of-concept study was performed on 76 honey samples. Targeted analysis indicated that 35 of 83 targeted molecules were detected in the 76 honey samples at concentrations below regulatory limits. Furthermore, untargeted metabolomic-like analyses highlighted 12 chlorinated xenobiotics, 1 of which was detected in lavender honey samples and identified as 2,6-dichlorobenzamide, a metabolite of dichlobenil, a pesticide banned in France since 2010. Lastly, multivariate statistical analyses discriminated honey samples according to their floral origin, and six discriminating metabolites were characterized thanks to the MS/MS experiments.
    Mots-clés : bees, contaminants, CSOB, data mining, Electrospray, food analysis, gas, high-resolution mass spectrometry, honey, liquid chromatography, Metabolite, metabolite identification, metabolomics, multi-residue analysis, multiresidue, performance liquid-chromatography, pesticides, POLE 3, pollutants, vegetables, veterinary drugs, waste-water, water samples, xenobiotics.

  • E. Darii, G. Saravanamuthu, I. G. Gut, et J. - C. Tabet, « Structural studies of the sBBI/trypsin non-covalent complex using covalent modification and mass spectrometry », Rapid Communications in Mass Spectrometry, vol. 28, nᵒ 5, p. 413-429.
    Résumé : RATIONALEThe study of protein recognition sites is crucial for understanding the mechanisms of protein interaction. Mass spectrometry can be a method of choice for the investigation of the contact surface within the protein non-covalent complexes. METHODSProbing the reactivity of essential amino acid residues of soybean Bowman-Birk inhibitor (sBBI) within the non-covalent sBBI/bovine trypsin complex was performed using covalent labeling by the BS3 cross-linker and charge tag with a quaternary ammonium group in combination with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) and tandem mass spectrometry (MS/MS) analysis. RESULTSSignificant modulation of the reactivity of essential K16 and S17 residues in the sBBI molecule upon binding to trypsin was established. The studies of sBBI proteolytic peptides with the same structure but carrying different labels using metastable dissociation in LIFT mode demonstrated that fragmentation pathways were oriented by used modification (BS3 cross-linker or charge tag). CONCLUSIONSThe effectiveness of the mass spectrometric approach including covalent modification for exploring protein-protein interaction sites has been demonstrated. The alteration of the reactivity of functionally important amino acid residues in the sBBI molecule is most likely related to changes in their microenvironment. It has been suggested that in the presence of charge tags fragmentation in LIFT mode proceeds through the formation of salt bridges between quaternary ammonium groups and acidic residues due to the occurrence of zwitterions (including basic and acidic residues). Despite the presence of one or several charge tags, fragmentation takes place yielding modulated b(i)/y(j) ion series depending on the positions of the tags. Copyright (c) 2014 John Wiley & Sons, Ltd.
    Mots-clés : bowman-birk inhibitor, charge-remote fragmentation, chemical cross-linking, collision-induced dissociation, crystal-structure, CSOB, ionizable groups, n-hydroxysuccinimide esters, POLE 3, protein-protein interactions, protonated peptides, soybean trypsin-inhibitors.

  • H. Dossmann, A. Schwarzenberg, D. Lesage, M. Perot-Taillandier, C. Afonso, B. C. de Miranda, et G. A. Garcia, « Vacuum Ultraviolet Photoionization Study of Gas Phase Vitamins A and B1 Using Aerosol Thermodesorption and Synchrotron Radiation », Journal of Physical Chemistry A, vol. 118, nᵒ 47, p. 11185-11192.
    Résumé : Gas-phase studies of biomolecules are often difficult to initiate because of the thermolability of these systems. Such studies are nevertheless important to determine fundamental intrinsic properties of the molecules. Here we present the valence shell photoionization of gas-phase vitamins A and B1 close to their ionization threshold. The study was performed by means of an aerosol thermodesorption source coupled to an electron/ion coincidence spectrometer and synchrotron radiation (SOLEIL facility, France). Ion yield curves were recorded for both molecules over a few electronvolt energy range and the threshold photoelectron spectrum was also obtained for vitamin A. Some fundamental properties were extracted for both ions such as adiabatic and the three first vertical ionization energies of retinol (IEad = 6.8 +/- 0.2 eV and IEvert = 7.4, 8.3, and 9.2 eV) and dissociation appearance energies for the main fragment ions of vitamin B1. Analysis of the data was supported by ab initio calculations which show a very good agreement with the experimental observations.
    Mots-clés : approximate, atoms, basis-sets, CSOB, energies, high-resolution, mass-spectrometry, POLE 3, retinoic acid, spectra, spin.

  • Q. Dumont et R. B. Cole, « Jean-Antoine Nollet: The Father of Experimental Electrospray », Mass Spectrometry Reviews, vol. 33, nᵒ 6, p. 418-423.
    Résumé : The development of electrospray ionization mass spectrometry (ESI-MS) was a 20th century occurrence that underwent rapid acceleration especially in the 1990's. However, long prior to its coupling with mass spectrometry, the electrification of liquids had been studied in a variety of contexts. Although initial reports describing cone formation upon electrification of water drops came out of England, the first true experiments investigating the electrospray phenomenon were performed in the middle of the 18th century by Abbe Jean-Antoine Nollet. The current report, associated with the French Regional Issue of Mass Spectrometry Reviews, examines the contributions of Abbe Nollet to the earliest understanding of the electrospray phenomenon. A description of his accomplishments is placed in the context of the societal and scientific developments of the Age of Enlightenment out of which Jean-Antoine Nollet arose. (c) 2013 Wiley Periodicals, Inc. Mass Spec Rev 33: 418-423, 2014.
    Mots-clés : CSOB, POLE 3.

  • G. A. Garcia, H. Dossmann, L. Nahon, S. Daly, et I. Powis, « Photoelectron circular dichroism and spectroscopy of trifluoromethyl- and methyl-oxirane: a comparative study », Physical Chemistry Chemical Physics, vol. 16, nᵒ 30, p. 16214-16224.
    Résumé : Photoelectron circular dichroism (PECD), a forward-backward asymmetry along the light propagation direction observed in the angular distribution of photoelectrons formed in the ionization of a chiral gas phase target with circularly polarized light, is becoming an established technique for chiral differentiation. In this work some of the fundamental and analytical properties of PECD are confirmed and explored further through a comparative study of the valence shell photoionization of enantiomerically pure trifluoromethyl-oxirane and methyloxirane, namely the sensitivity of PECD to the initial orbital and to chemical substitution. The recorded PECD experimental data and corresponding continuum multiple scattering calculations for the outermost orbitals obtained at various photon energies reveal the dramatic effect of substituting the CF3 and CH3 groups attached at the asymmetric chiral center. The previously unknown trifluoromethyl-oxirane ion spectroscopy and the fragmentation pattern measured by threshold electron/ion coincidence techniques over the first four eVs above the ionization threshold are also presented in this work and assigned through the use of ab initio calculations. The state-selected photochemistry and threshold electron spectroscopy of methyl-oxirane have additionally been recorded to complement previous spectroscopic studies.
    Mots-clés : angular-distribution, asymmetry, camphor, chiral molecules, co molecule, CSOB, enantiomers, gas-phase, photoionization, POLE 3, synchrotron-radiation, variable-polarization.

  • C. Hubert, A. Schwarzenberg, H. Dossmann, R. B. Cole, X. Machuron-Mandard, et J. - C. Tabet, « Clarification of the 30 Da releases from the [M-H](-) and M-. ions of trinitrotoluene by electrospray high resolution mass spectrometry », Journal of Mass Spectrometry, vol. 49, nᵒ 4, p. 327-330.
    Mots-clés : ch2o, CSOB, esi, explosives, high resolution, mass spectrometry, POLE 3, tnt.

  • F. Ichou, A. Schwarzenberg, D. Lesage, S. Alves, C. Junot, X. Machuron-Mandard, et J. - C. Tabet, « Comparison of the activation time effects and the internal energy distributions for the CID, PQD and HCD excitation modes », Journal of Mass Spectrometry, vol. 49, nᵒ 6, p. 498-508.
    Résumé : Reproducibility among different types of excitation modes is a major bottleneck in the field of tandem mass spectrometry library development in metabolomics. In this study, we specifically evaluated the influence of collision voltage and activation time parameters on tandem mass spectrometry spectra for various excitation modes [collision-induced dissociation (CID), pulsed Q dissociation (PQD) and higher-energy collision dissociation (HCD)] of Orbitrap-based instruments. For this purpose, internal energy deposition was probed using an approach based on Rice-Rampserger-Kassel-Marcus modeling with three thermometer compounds of different degree of freedom (69, 228 and 420) and a thermal model. This model treats consecutively the activation and decomposition steps, and the survival precursor ion populations are characterized by truncated Maxwell-Boltzmann internal energy distributions. This study demonstrates that the activation time has a significant impact on MS/MS spectra using the CID and PQD modes. The proposed model seems suitable to describe the multiple collision regime in the PQD and HCD modes. Linear relationships between mean internal energy and collision voltage are shown for the latter modes and the three thermometer molecules. These results suggest that a calibration based on the collision voltage should provide reproducible for PQD, HCD to be compared with CID in tandem in space instruments. However, an important signal loss is observed in PQD excitation mode whatever the mass of the studied compounds, which may affect not only parent ions but also fragment ions depending on the fragmentation parameters. A calibration approach for the CID mode based on the variation of activation time parameter is more appropriate than one based on collision voltage. In fact, the activation time parameter in CID induces a modification of the collisional regime and thus helps control the orientation of the fragmentation pathways (competitive or consecutive dissociations). Copyright (c) 2014 John Wiley & Sons, Ltd.
    Mots-clés : activation time, cid, collisional activation, CSOB, electrospray-ionization, fragmentation, gas reactions, hcd, induced dissociation spectra, internal energy distribution, metabolomics, POLE 3, pqd, protonated leucine-enkephalin, quadrupole ion-trap, RRKM modeling, surface-induced dissociation, tandem mass-spectrometry, Temperature.

  • C. Le Vot, C. Afonso, C. Beaugrand, et J. - C. Tabet, « Penning ionization-FT-ICR: Application to diesel fuel analysis », International Journal of Mass Spectrometry, vol. 367, p. 35-42.
    Résumé : The Penning ionization (Pel) source uses atoms of rare gases or molecules (N-2) excited to give a flux of metastable atoms or molecules (A*) able by collision to ionize a target molecule (M) on the condition that the process is exothermic (i.e., IE(M)< EE(A)). As electron ionization, PeI allows the ionization of apolar species such as saturated hydrocarbons yielding molecular ions. In this work we present the application of vacuum PeI source coupled with a FT-ICR instrument for the characterization of a diesel fuel. Argon and krypton, as metastable gas, allow reducing significantly the fragmentation extent compared to electron ionization. Unlike with an atmospheric pressure source, the use of a vacuum source allows a good control of the ionization conditions with the absence of oxygen or other reactant such as water. (c) 2014 Elsevier B.V. All rights reserved.
    Mots-clés : aromatic-compounds, benzothiophene, CSOB, Diesel fuel, elemental composition, ft-icr, hydrocarbons, identification, Metastable, oil, Penning ionization, POLE 3, pressure chemical-ionization, refinery streams, resolution, resonance mass-spectrometry.

  • D. Lesage, A. Milet, A. Memboeuf, J. Blu, A. E. Greene, J. - C. Tabet, et Y. Gimbert, « The Pauson-Khand Mechanism Revisited: Origin of CO in the Final Product », Angewandte Chemie-International Edition, vol. 53, nᵒ 7, p. 1939-1942.
    Résumé : The mechanism of the Pauson-Khand reaction has been studied by mass spectrometry and it has been found, through ion-molecule reaction with (CO)-C-13, that the carbon monoxide incorporated into the product cyclopentenone is one that has been retained within the complex. Theoretical and kinetic calculations support this finding, which provides a complementary explanation for the effect of Pauson-Khand promoters.
    Mots-clés : cobalt, CSOB, cyclizations, density functional calculations, gas-phase reactions, ionization mass-spectrometry, mass spectrometry, n-oxide, POLE 3, Reaction mechanisms.

  • X. Liu et R. B. Cole, « "Best Match" Model and Effect of Na+/H+ Exchange on Anion Attachment to Peptides and Stability of Formed Adducts in Negative Ion Electrospray Mass Spectrometry », Journal of the American Society for Mass Spectrometry, vol. 25, nᵒ 2, p. 204-213.
    Résumé : The "Best Match" model has been extended to account for the role that Na+/H+ exchange plays on anion attachment in negative ion electrospray. Without any Na+/H+ exchange on (Glu) fibrinopeptide B, the higher basicity anions F- and CH3COO- can hardly form observable adducts; however, after multiple Na+/H+ exchanges, adduct formation is enabled. Moreover, dissociation pathways of CF3COO- adducts with singly deprotonated peptides that have undergone 0 to 3 Na+/H+ exchanges exhibit a shift in CID product ions from losing predominately CF3COOH (case of 0 Na+/H+ exchanges) to losing predominately CF3COO- (case of 3 Na+/H+ exchanges). These phenomena can be rationalized by considering that Na+ cations exchange at, and serve to "block", the most acidic sites, thereby forcing implicated anions to attach to lower acidity protons. In addition to forming ion pairs with carboxylate groups, Na+ also participates in formation of tri-atomic ions of the form ANaA(-) during adduct dissociation. The fact that low gas-phase basicity (GB) anions preferentially form ANaA(-) species, even though high GB anions form more stable tri-atomic species, indicates that the monatomic ions were not in close contact in the initial adduct. The propensity for formation of stable anionic adducts is dependent on the degree of matching between anion GBs and GB(app) of deprotonated sites on the peptide. The GB(app) is raised dramatically as the charge state of the peptide increases via a through-space effect. The presence of Na+ on carboxylate sites substantially decreases the GB(app) by neutralizing these sites, while slightly increasing the intrinsic GBs by an inductive effect.
    Mots-clés : absence, Anion attachment, Anionic adducts, Best Match model, charge-state, CSOB, Gas-phase acidity, Gas-phase basicity, ionization, Negative ion, Peptide adducts, POLE 3, protein ions, solvent.

  • X. Liu, J. - C. Tabet, et R. B. Cole, « Evidence for ion-ion interactions between peptides and anions (HSO4- or ClO4-) derived from high-acidity acids », Journal of Mass Spectrometry, vol. 49, nᵒ 6, p. 490-497.
    Résumé : The existence of gas-phase electrostatic ion-ion interactions between protonated sites on peptides ([Glu] Fibrinopeptide B, Angiotensin I and [Asn1, Val5]-Angiotensin II) and attaching anions (ClO4- and HSO4-) derived from strong inorganic acids has been confirmed by CID MS/MS. Evidence for ion-ion interactions comes especially from the product ions formed during the first dissociation step, where, in addition to the expected loss of the anion or neutral acid, other product ions are also observed that require covalent bond cleavage (i.e. H2O loss when several carboxylate groups are present, or NH3 loss when only one carboxylate group is present). For [[Glu] Fibrinopeptide B+HSO4]-, under CID, H2O water loss was found to require less energy than H2SO4 departure. This indicates that the interaction between HSO4- and the peptide is stronger than the covalent bond holding the hydroxyl group, and must be an ion-ion interaction. The strength and stability of this type of ion-pairing interaction are highly dependent on the accessibility of additional mobile charges to the site. Positive mobile charges such as protons from the peptide can be transferred to the attaching anion to possibly form a neutral that may depart from the complex. Alternatively, an ion-ion interaction can be disrupted by a competing proximal additional negatively charged site of the peptide that can potentially form a salt bridge with the positively charged site and thereby facilitate the attaching anion's departure. Copyright (c) 2014 John Wiley & Sons, Ltd.
    Mots-clés : adduct, Anion attachment, best match model, bronsted acids, cations, complexes, CSOB, gas-phase acidity, mass-spectrometry, POLE 3, protein ions, salt bridge, salt-bridge interactions, Stability.

  • A. Martelet, G. L'Hostis, P. Tavares, S. Brasiles, F. Fenaille, C. Rozand, A. Theretz, G. Gervasi, J. - C. Tabet, E. Ezan, C. Junot, B. H. Muller, et F. Becher, « Bacterial Detection Using Unlabeled Phage Amplification and Mass Spectrometry through Structural and Nonstructural Phage Markers », Journal of Proteome Research, vol. 13, nᵒ 3, p. 1450-1465.
    Résumé : According to the World Health Organization, food safety is an essential public health priority. In this context, we report a relevant proof of feasibility for the indirect specific detection of bacteria in food samples using unlabeled phage amplification coupled to ESI mass spectrometry analysis and illustrated with the model phage systems T4 and SPP1. High-resolving power mass spectrometry analysis (including bottom-up and top-down protein analysis) was used for the discovery of specific markers of phage infection. Structural components of the viral particle and nonstructural proteins encoded by the phage genome were identified. Then, targeted detection of these markers was performed on a triple quadrupole mass spectrometer operating in the selected reaction monitoring mode. E. coli at 1 X 10(5), 5 X 10(5), and 1 X 10(6) CFU/mL concentrations was successfully detected after only a 2 h infection time by monitoring phage T4 structural markers in Luria-Bertani broth, orange juice, and French bean stew ("cassoulet") matrices. Reproducible detection of nonstructural markers was also demonstrated, particularly when a high titer of input phages was required to achieve successful amplification. This strategy provides a highly time-effective and sensitive assay for bacterial detection.
    Mots-clés : assay, bacillus-subtilis, bacterial detection, bacteriophage spp1, CSOB, gene, high-resolving power mass spectrometry, identification, ionization, marker discovery, nonstructural protein, pathogen detection, POLE 3, protein-synthesis, proteomics, quantification, srm, unlabeled phage.

  • J. - C. Martin, M. Maillot, G. Mazerolles, A. Verdu, B. Lyan, C. Migné, C. Defoort, C. Canlet, C. Junot, C. Guillou, C. Manach, D. Jabob, D. J. - R. Bouveresse, E. Paris, E. Pujos-Guillot, F. Jourdan, F. Giacomoni, F. Courant, G. Favé, G. L. Gall, H. Chassaigne, J. - C. Tabet, J. - F. Martin, J. - P. Antignac, L. Shintu, M. Defernez, M. Philo, M. - C. Alexandre-Gouaubau, M. - J. Amiot-Carlin, M. Bossis, M. N. Triba, N. Stojilkovic, N. Banzet, R. Molinié, R. Bott, S. Goulitquer, S. Caldarelli, et D. N. Rutledge, « Can we trust untargeted metabolomics? Results of the metabo-ring initiative, a large-scale, multi-instrument inter-laboratory study », Metabolomics, vol. 11, p. 807-821.
    Mots-clés : Biochemistry, general, Biomedicine general, Cell Biology, CSOB, Developmental Biology, Inter-laboratory, mass spectrometry, Metabolic fingerprinting, Molecular Medicine, Nuclear magnetic resonance, POLE 3, Untargeted metabolomics.

  • F. Mauger, J. - C. Tabet, et I. G. Gut, « A revisit of high collision energy effects on collision-induced dissociation spectra using matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-LIFT-TOF/TOF): application to the sequencing of RNA/DNA chimeras », Rapid Communications in Mass Spectrometry, vol. 28, nᵒ 13, p. 1433-1443.
    Résumé : RATIONALEHigh-energy collision-induced dissociation (CID) spectra of isomeric RNA/DNA chimeras using matrix-assisted laser desorption/ionization time-of-flight LIFT mass spectrometry (MALDI-LIFT-TOF/TOF) can potentially be applied for an exhaustive fragment characterization in a nucleic acid sequencing scheme. These chimeras contain deoxynucleotides and at the 3'-end a ribonucleotide with a 3'-phosphate group. METHODSDeprotonated RNA/DNA chimeras of 4-, 5-, 7- and 10-mers are analyzed by CID. This enhances consecutive dissociations from both the precursor and prompt product anions generated by MALDI and metastable fragmentations prior to entering the LIFT cell. RESULTSGas-phase fragmentations of 4- and 5-mers produced many fragment ions, from base release prior to consecutive cleavage of the nucleotide phosphate bond linkage phosphate. The unusual a4- product ion is a specific and diagnostic dissociation of the 4-mer if the ribonucleotide contains cytosine. As the size of RNA/DNA chimeras increase, several abundant product ions are generated mainly from zwitterionic forms (deprotonated phosphate ester and protonated base sites): [(M-H)-BiH]-, [ai-BiH]-, wj-, [wj, (ai-BiH)]- (if BiT) as internal product ion, and more rarely [wj-BiH]-. The absence of the majority of the [ai-BiH]- series although the wj- series suggested that the higher critical energy processes with a loose transition state are favored yielding the wj- series. A large number of abundant fragment ions are detected which enable each isomer to be sequenced. CONCLUSIONSThis sequencing method is high-throughput, accurate and could be used to sequence isomers of up to 10-mers and also oligonucleotides of unknown sequence. However, RNA/DNA chimeras without thymine must be sufficiently concentrated to reach desorption of deprotonated molecular species to be selected in LIFT to produce all fragment ions within measurable abundances. Copyright (c) 2014 John Wiley & Sons, Ltd.
    Mots-clés : alkali cleavage, CSOB, DNA, in-source fragmentation, metastable decay, modified oligonucleotides, nucleic-acids, oligodeoxynucleotides, POLE 3, post-source-decay, rna fragmentation, tof-ms.

  • S. S. Quadri, R. E. Stratford, S. M. Boue, et R. B. Cole, « Identification of Glyceollin Metabolites Derived from Conjugation with Glutathione and Glucuronic Acid in Male ZDSD Rats by Online Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry », Journal of Agricultural and Food Chemistry, vol. 62, nᵒ 12, p. 2692-2700.
    Résumé : Glyceollin-related metabolites produced in rats following oral glyceollin administration were screened in plasma, feces, and urine, and these metabolites were identified by precursor and product ion scanning using liquid chromatography coupled online with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Precursor ion scanning in the negative ion (NI) mode was used to identify all glyceollin metabolites based on production of a diagnostic radical product ion (m/z 148) upon decomposition. Using this approach, precursor peaks of interest were found at m/z 474 and 531. Tandem mass spectra of these two peaks allowed us to characterize them as byproducts of glutathione conjugation. The peak at m/z 474 was identified as the deprotonated cysteinyl conjugate of glyceollins with an addition of an oxygen atom, whereas m/z 531 was identified as the deprotonated cysteinylglyceine glyceollin conjugate plus an oxygen. These results were confirmed by positive ion (PI) mode analyses. Mercapturic acid conjugates of glyceollins were also identified in NI mode. In addition, glucuronidation of glyceollins was observed, giving a peak at m/z 513 corresponding to the deprotonated conjugate. Production of glucuronic acid conjugates of glyceollins was confirmed in vitro in rat liver microsomes. Neither glutathione conjugation byproducts nor glucuronic acid conjugates of glyceollins have been previously reported.
    Mots-clés : cancer, CSOB, flavonoids, genistein, in-vitro, isoflavones, model, Pharmacokinetics, phase I metabolism, phase II metabolism, phytoalexins, phytochemicals, phytoestrogens, POLE 3, reactive oxygen species, soy, soybean glyceollins, women.

  • E. Rathahao-Paris, A. Paris, J. Bursztyka, J. - P. Jaeg, J. - P. Cravedi, et L. Debrauwer, « Identification of xenobiotic metabolites from biological fluids using flow injection analysis high-resolution mass spectrometry and post-acquisition data filtering », Rapid Communications in Mass Spectrometry, vol. 28, nᵒ 24, p. 2713-2722.
    Résumé : RATIONALE Concern for public health entails the need to evaluate the degree of exposure of population to toxicants. To do this, robust high-throughput approaches are required to be able to perform a large number of analyses in cohort studies. In this study, a data-filtering procedure was applied to mass spectral data acquired by direct analysis of biological fluids leading to rapid detection of metabolites in a model xenobiotic system. METHODS Flow injection analysis (FIA) coupled to negative electrospray ionization (ESI)-LTQ Orbitrap Fourier transform mass spectrometry was used to directly analyze urine of rats treated with vinclozolin. Tandem mass spectrometry (MS/MS) experiments were subsequently performed for confirmation of a new metabolite structure. The isotope filtering based on the difference between accurate masses of 35Cl and 37Cl was applied to the raw data for the specific detection of ions containing at least one chlorine atom. RESULTS Seven metabolites of vinclozolin were manually identified thanks to the characteristic isotope pattern of dichlorinated compounds. A new metabolite of vinclozolin was detected for the first time and identified as a sulfate conjugate. The application of an isotope-filtering procedure allowed the selective extraction of pertinent signals from the data. The processed mass spectrum was greatly simplified, significantly facilitating the detection of the seven metabolites previously identified. CONCLUSIONS The use of FIA-HRMS in combination with dedicated bio-informatics data processing is shown to be an efficient approach for the rapid detection of metabolites in biological fluids. This is a very promising high-throughput approach for rapid characterization of the exposure status to xenobiotics. Copyright © 2014 John Wiley & Sons, Ltd.
    Mots-clés : CSOB, POLE 3.

  • A. Schwarzenberg, H. Dossmann, R. B. Cole, X. Machuron-Mandard, et J. - C. Tabet, « Differentiation of isomeric dinitrotoluenes and aminodinitrotoluenes using electrospray high resolution mass spectrometry », Journal of Mass Spectrometry, vol. 49, nᵒ 12, p. 1330-1337.
    Résumé : Explosive detection and identification play an important role in the environmental and forensic sciences. However, accurate identification of isomeric compounds remains a challenging task for current analytical methods. The combination of electrospray multistage mass spectrometry (ESI-MSn) and high resolution mass spectrometry (HRMS) is a powerful tool for the structure characterization of isomeric compounds. We show herein that resonant ion activation performed in a linear quadrupole ion trap allows the differentiation of dinitrotoluene isomers as well as aminodinitrotoluene isomers. The explosive-related compounds: 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2-amino-4,6-dinitrotoluene (2A-4,6-DNT) and 4-amino-2,6-dinitrotoluene (4A-2,6-DNT) were analyzed by ESI-MS in the negative ion mode; they produced mainly deprotonated molecules [M-H](-). Subsequent low resolution MSn experiments provided support for fragment ion assignments and determination of consecutive dissociation pathways. Resonant activation of deprotonated dinitrotoluene isomers gave different fragment ions according to the position of the nitro and amino groups on the toluene backbone. Fragment ion identification was bolstered by accurate mass measurements performed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS). Notably, unexpected results were found from accurate mass measurements performed at high resolution for 2,6-DNT where a 30-Da loss was observed that corresponds to CH2O departure instead of the expected isobaric NO center dot loss. Moreover, 2,4-DNT showed a diagnostic fragment ion at m/z 116, allowing the unambiguous distinction between 2,4- and 2,6-DNT isomers. Here, CH2O loss is hindered by the presence of an amino group in both 2A-4,6-DNT and 4A-2,6-DNT isomers, but nevertheless, these isomers showed significant differences in their fragmentation sequences, thus allowing their differentiation. DFT calculations were also performed to support experimental observations. Copyright (c) 2014 John Wiley & Sons, Ltd.
    Mots-clés : aminodinitrotoluenes, CSOB, dinitrotoluenes, esi-hrms, explosives, gas-chromatography, high resolution mass spectrometry, ionization, ions, isomer differentiation, liquid-chromatography, nitramine, nitrate ester explosives, POLE 3, spectra, trace analysis, trinitrotoluene, water.

  • N. Stojiljkovic, A. Paris, P. Garcia, M. - A. Popot, Y. Bonnaire, J. - C. Tabet, et C. Junot, « Evaluation of horse urine sample preparation methods for metabolomics using LC coupled to HRMS », Bioanalysis, vol. 6, nᵒ 6, p. 785-803.


  • S. Alves, E. Rathahao-Paris, et J. C. Tabet, « Potential of Fourier Transform Mass Spectrometry for High-Throughput Metabolomics Analysis », in Advances in Botanical Research, vol. 67, Elsevier, 2013, p. 219-302.

  • C. Bennaceur, C. Afonso, S. Alves, A. Bossée, et J. - C. Tabet, « Instrumental Dependent Dissociations of n-Propyl/Isopropyl Phosphonate Isomers: Evaluation of Resonant and Non-Resonant Vibrational Activations », Journal of The American Society for Mass Spectrometry, vol. 24, nᵒ 8, p. 1260-1270.

  • S. Bourgoin-Voillard, C. Afonso, D. Lesage, E. - L. Zins, J. - C. Tabet, et P. B. Armentrout, « Critical Evaluation of Kinetic Method Measurements: Possible Origins of Nonlinear Effects », Journal of The American Society for Mass Spectrometry, vol. 24, nᵒ 3, p. 365-380.

  • M. N. Boutaghou, C. M. Kronfel, L. S. Hernandez, A. Biswas, W. M. Schluchter, et R. B. Cole, « Direct differentiation of A-ring single attachment versus A- and D-ring double attachment of phycoerythrobilin chromophores to phycobiliproteins using MALDI mass spectrometry », Journal of Mass Spectrometry, vol. 48, nᵒ 2, p. 187-192.
    Résumé : Bilin chromophore attachment to phycobiliproteins is an enzyme-catalyzed post-translational modification process. Bilin-lyases attach a bilin chromophore to their cognate protein through a thioether bond between the chromophore and a cysteine moiety. Bilin chromophores are attached to their phycobiliproteins through the 31 carbon of the bilin. Double attachment may also occur, and in this case, carbons 31 and 181 of the bilin are both forming covalent linkages to cysteine moieties. There is a mass spectrometric limitation when examining tryptic peptides containing two (or more) cysteines if one seeks to ascertain whether chromopeptides are singly or doubly attached. The problem is that singly and doubly attached chromopeptides appear at the same m/z value; thus, up until the present, only NMR analysis has been successful at determining whether the chromophore is singly or doubly attached. We report in this work a new, fast and accurate method for discriminating singly from doubly attached chromophores using MALDI-TOF mass spectrometry. This method was developed from mass spectral analysis of chromopeptides that had undergone in vitro or in vivo attachment of bilin chromophores to phycobiliproteins. Distinction is based on a characteristic neutral loss that appears in the MALDI-TOF mass spectrum only when the bilin is singly attached. Copyright (c) 2013 John Wiley & Sons, Ltd.
    Mots-clés : b-phycoerythrin, beta-subunits, bilin linkage diversity, bilin lyase, biliproteins, c-phycocyanin, chromophore, crystal-structure, CSOB, cyanobacteria, Fremyella diplosiphon, light harvesting, maldi ms, phycobiliprotein, phycoerythrobilin, POLE 3, r-phycoerythrin, resolution, sites.

  • B. Brahim, S. Alves, R. B. Cole, et J. - C. Tabet, « Charge Enhancement of Single-Stranded DNA in Negative Electrospray Ionization Using the Supercharging Reagent Meta-nitrobenzyl Alcohol », Journal of the American Society for Mass Spectrometry, vol. 24, nᵒ 12, p. 1988-1996.
    Résumé : Charge enhancement of single-stranded oligonucleotide ions in negative ESI mode is investigated. The employed reagent, meta-nitrobenzyl alcohol (m-NBA), was found to improve total signal intensity (I-tot), increase the highest observed charge states (z(high)), and raise the average charge states (z(avg)) of all tested oligonucleotides analyzed in negative ESI. To quantify these increases, signal enhancement ratios (SER1%) and charge enhancement coefficients (CEC1%) were introduced. The SER1%, (defined as the quotient of total oligonucleotide ion abundances with 1 % m-NBA divided by total oligonucleotide abundance without m-NBA) was found to be greater than unity for every oligonucleotide tested. The CEC1% values (defined as the average charge state in the presence of 1 % m-NBA minus the average charge state in the absence of m-NBA) were found to be uniformly positive. Upon close inspection, the degree of charge enhancement for longer oligonucleotides was found to be dependent upon thymine density (i.e., the number and the location of phospho-thymidine units). A correlation between the charge enhancement induced by the presence of m-NBA and the apparent gas-phase acidity (largely determined by the sequence of thymine units but also by the presence of protons on other nucleobases) of multiply deprotonated oligonucleotide species, was thus established. Ammonium cations appeared to be directly involved in the m-NBA supercharging mechanism, and their role seems to be consistent with previously postulated ESI mechanisms describing desorption/ionization of single-stranded DNA into the gas phase.
    Mots-clés : Ammonium counter-ion, Apparent gas-phase acidity, capture dissociation, collision-induced dissociation, CSOB, Desolvation, Electrospray, esi-ms, gas-phase, Gas-phase acidity, ion mobility, Meta-nitrobenzyl alcohol, nucleic-acids, oligonucleotides, POLE 3, product ions, Single-stranded DNA, state distributions, Supercharging, tandem mass-spectrometry.

  • H. Dossmann, C. Afonso, J. - C. Tabet, et E. Uggerud, « Unimolecular dissociation characteristics of cationic complexes between nicotinic acid and Cu(II) and Ni(II) », International Journal of Mass Spectrometry, vol. 354-355, p. 165-174.

  • Y. Gimbert, L. Fensterbank, V. Gandon, J. - P. Goddard, et D. Lesage, « Ligand Effect in Platinum-Catalyzed Cycloisomerization of 1,6-Enynes: Water or Carbon Monoxide, a Similar Role despite Distinct Electronic Properties? », Organometallics, vol. 32, nᵒ 2, p. 374-376.
    Résumé : The PtCl2-catalyzed cycloisomerization of 1,6-enynes is considerably accelerated in the presence of carbon monoxide. The effect of CO has been explained by the reinforcement of the electrophilicity of the alkyne moiety once ligated to the pi-acidic [PtCl2(CO)] fragment. However, platinum is also described as wealdy capable of back-donation toward CO. A theoretical study has been carried out to shed light on this apparent contradiction. An alternative explanation based on the approach of CO onto the [PtCl2(eta(4)-(1,6-enyne))] complex is proposed. When CO is ligated to PtCl2, the triple-bond coordination is favored, yet there is no positive influence on the formation of the cyclopropylcarbene key intermediate. The role of CO is actually comparable to that of a water molecule.
    Mots-clés : acetylenes, activation, alkenes, chloro complexes, competition, COS, CSOB, enynes, halides, MACO, palladium(ii), POLE 1, POLE 3, reactivity, skeletal reorganization.

  • C. Hubert, H. Dossmann, X. Machuron-Mandard, et J. - C. Tabet, « ESI formation of a Meisenheimer complex from tetryl and its unusual dissociation », Journal of Mass Spectrometry, vol. 48, nᵒ 3, p. 306-311.

  • F. Ichou, D. Lesage, X. Machuron-Mandard, C. Junot, R. B. Cole, et J. - C. Tabet, « Collision cell pressure effect on CID spectra pattern using triple quadrupole instruments: a RRKM modeling », Journal of Mass Spectrometry, vol. 48, nᵒ 2, p. 179-186.
    Résumé : Control of the ion internal energy in mass spectrometry is needed to establish a workable mass spectral library. The purpose of this study is to understand and to compare the pressure effects on the collision-induced dissociation (CID) spectrum pattern recorded using triple quadrupole instruments. The monoprotonated Leucine enkephalin [YGGFL, H+] was used as a thermometer molecule to calibrate the electrospray ionization (ESI) and the CID internal energies deposited on the molecular species and the time scale of ion decompositions. The survival yield and the ratio of a4/b4 fragment ions were mainly monitored. The energy uptake for the ESI source geometry used in our study has no impact on the CID spectrum fingerprint. The collision cell pressure for the [YGGFL, H+] has a major influence on the SY curves slope and on the experimental time scale. To demonstrate the pressure effect on internal energy distribution, three models (threshold, thermal and collisional) based on RRKM theory were built using the Masskinetics software. As a result, the limit of each model is discussed, and the investigation demonstrates that the thermal model, using truncated Maxwell-Boltzmann internal energy distribution, is well-suited for simulating the experimental data at high pressure widely used in the analytical conditions. Copyright (c) 2013 John Wiley & Sons, Ltd.
    Mots-clés : activation, calibration, CSOB, distributions, electrospray-ionization, fragmentation, guided ion-beam, induced dissociation, internal energy-distribution, Leucine-enkephalin, MassKinetics, POLE 3, pressure effect, RRKM modeling, tandem mass-spectrometry, triple quadrupole.

  • G. N. Khairallah, C. C. L. Thum, D. Lesage, J. - C. Tabet, et R. A. J. O’Hair, « Gas-Phase Formation and Fragmentation Reactions of the Organomagnesates [RMgX2]− », Organometallics, vol. 32, nᵒ 8, p. 2319-2328.

  • C. M. Kronfel, A. P. Kuzin, F. Forouhar, A. Biswas, M. Su, S. Lew, J. Seetharaman, R. Xiao, J. K. Everett, L. - C. Ma, T. B. Acton, G. T. Montelione, J. F. Hunt, C. E. C. Paul, T. M. Dragomani, M. N. Boutaghou, R. B. Cole, C. Riml, R. M. Alvey, D. A. Bryant, et W. M. Schluchter, « Structural and Biochemical Characterization of the Bilin Lyase CpcS from Thermosynechococcus elongatus », Biochemistry, vol. 52, nᵒ 48, p. 8663-8676.
    Résumé : Cyanobacterial phycobiliproteins have evolved to capture light energy over most of the visible spectrum due to their bilin chromophores, which are linear tetrapyrroles that have been covalently attached by enzymes called bilin lyases. We report here the crystal structure of a bilin lyase of the CpcS family from Thermosynechococcus elongatus (TeCpcS-III). TeCpcS-III is a 10-stranded beta barrel with two alpha helices and belongs to the lipocalin structural family. TeCpcS-III catalyzes both cognate as well as noncognate bilin a

    ttachment to a variety of phycobiliprotein subunits. TeCpcS-III ligates phycocyanobilin, phycoerythrobilin, and phytochromobilin to the alpha and beta subunits of allophycocyanin and to the beta subunit of phycocyanin at the Cys82-equivalent position in all cases. The active form of TeCpcS-III is a dimer, which is consistent with the structure observed in the crystal. With the use of the UnaG protein and its association with bilirubin as a guide, a model for the association between the native substrate, phycocyanobilin, and TeCpcS was produced.
    Mots-clés : binding-protein, chromophore attachment, core-membrane linker, crystal-structure analysis, CSOB, cyanobacterial isca homolog, escherichia-coli, heme oxygenase, phycobiliprotein beta-subunits, POLE 3, sp pcc 6803, synechococcus sp pcc-7002.

  • M. M. Lorion, B. Matt, S. Alves, A. Proust, G. Poli, J. Oble, et G. Izzet, « Versatile Post-functionalization of Polyoxometalate Platforms By Using An Unprecedented Range of Palladium-Catalyzed Coupling Reactions », Chemistry - A European Journal, vol. 19, nᵒ 38, p. 12607-12612.
    Mots-clés : Allylic alkylation, clusters, cross-coupling, CSOB, dawson, E-POM, head groups, Heck reaction, hybrid, Keggin, organic-inorganic hybrids, Palladium, POLE 1, POLE 2, POLE 3, Polyoxometalates, polyoxotungstates, POM, ROCS, SSO, surfaces, surfactants.

  • B. Matt, X. Xiang, A. L. Kaledin, N. Han, J. Moussa, H. Amouri, S. Alves, C. L. Hill, T. Lian, D. G. Musaev, G. Izzet, et A. Proust, « Long lived charge separation in iridium(III)-photosensitized polyoxometalates: synthesis, photophysical and computational studies of organometallic–redox tunable oxide assemblies », Chemical Science, vol. 4, nᵒ 4, p. 1737-1745.
    Résumé : Keggin and Dawson-type polyoxometalates (POMs) covalently grafted to heteroleptic cyclometalated iridium(iii) complexes (POM–[Ir] dyads) have been prepared by postfunctionalization of organosilyl and organotin POM derivatives. Electronic properties of these 4 photosensitized POM–[Ir] dyads were evaluated by
    Mots-clés : ARC, CSOB, E-POM, POLE 1, POLE 2, POLE 3, POM.

  • M. - A. Maubert, E. Quévrain, E. Capton, J. P. Grill, G. Thomas, M. Bachelet, D. Rainteau, G. Trugnan, J. - C. Tabet, J. Masliah, et C. Afonso, « High-resolution mass spectrometry and partial <i>de novo</i> sequencing constitute a useful approach for determining the profile of chemokine secretion following the stimulation of human intestinal epithelial cells », Rapid Communications in Mass Spectrometry, vol. 27, nᵒ 19, p. 2179-2187.

  • S. S. Quadri, R. E. Stratford, S. M. Boué, et R. B. Cole, « Screening and Identification of Glyceollins and Their Metabolites by Electrospray Ionization Tandem Mass Spectrometry with Precursor Ion Scanning », Analytical Chemistry, vol. 85, nᵒ 3, p. 1727-1733.
    Résumé : A method has been developed for screening glyceollins and their metabolites based on precursor ion scanning. Under higher-energy collision conditions with the employment of a triple quadrupole mass spectrometer in the negative ion mode, deprotonated glyceollin precursors yield a diagnostic radical product ion at m/z 148. We propose this resonance-stabilized radical anion, formed in violation of the even-electron rule, to be diagnostic of glyceollins and glyceollin metabolites. Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) established that scanning for precursors of m/z 148 can identify glyceollins and their metabolites from plasma samples originating from rats dosed with glyceollins. Precursor peaks of interest were found at m/z 337, 353, 355, 417, and 433. The peak at m/z 337 corresponds to deprotonated glyceollins, whereas the others represent metabolites of glyceollins. Accurate mass measurement confirmed m/z 417 to be a sulfated metabolite of glyceollins. The peak at m/z 433 is also sulfated, but it contains an additional oxygen, as c!onfirmed by accurate mass measurement. The latter metabolite differs from the former likely by the replacement of a hydrogen with a hydroxyl moiety. The peaks at m/z 353 and 355 are proposed to correspond to hydroxylated metabolites of glyceollins, wherein the latter additionally undergoes a double bond reduction.
    Mots-clés : CSOB, POLE 3.

  • A. Schwarzenberg, F. Ichou, R. B. Cole, X. Machuron-Mandard, C. Junot, D. Lesage, et J. - C. Tabet, « Identification tree based on fragmentation rules for structure elucidation of organophosphorus esters by electrospray mass spectrometry », Journal of Mass Spectrometry, vol. 48, nᵒ 5, p. 576-586.
    Résumé : Organophosphorus compounds have played important roles as pesticides, chemical warfare agents and extractors of radioactive material. Structural elucidation of phosphonates poses a particular challenge because their initial forms can be hydrolyzed, thus, degradation products may predominate in samples acquired in the field. The analysis of non-volatile organophosphorus compounds and their degradation products is possible using electrospray tandem mass spectrometry ESI-MS/MS. Here, we present a generic strategy that allows the unambiguous identification of substituents for two families of organophosphorus compounds: the phosphonates and phosphates. General fragmentation rules were deduced based on the study of decomposition pathways of 55 organophosphorus esters, including examples found in the literature. Multistage MS (MSn) experiments at high resolution in a hybrid mass spectrometer provide accurate mass measurements, whereas collision-induced dissociation experiments in a triple quadrupole give access to small fragment ions. The creation of a specific nomenclature for each possible structure of organophosphorus compound, depending on the alkyl side chain linked to the oxygen, was achieved by applying these fragmentation rules. This led to the creation of an identification tree' based upon the unique consecutive decomposition pathways uncovered for each individual compound. Hence, seven structural motifs were created that orient an unequivocal identification using the identification tree'. Despite the similar structures of the ensemble of phosphate and phosphonate esters, distinct identifications based upon characteristic neutral losses and diagnostic fragment ions were possible in all cases. Copyright (c) 2013 John Wiley & Sons, Ltd.
    Mots-clés : chemical warfare agents, CSOB, decontamination solutions, degradation-products, elucidation, fragmentation tree, high resolution, ionization, mass spectrometry, msn, nmr-spectroscopy, organophosphorus, POLE 3, spectral trees, structure.

  • T. Tripković, C. Charvy, S. Alves, Ađ. Lolić, R. M. Baošić, S. D. Nikolić-Mandić, et J. C. Tabet, « Identification of protein binders in artworks by MALDI-TOF/TOF tandem mass spectrometry », Talanta, vol. 113, p. 49-61.

  • S. Vitcher, C. Charvy, L. Dudragne, et J. - C. Tabet, « Characterization of an Electron Ionization Source Trap Operating in the Presence of a Magnetic Field Through Computer Simulation », Journal of The American Society for Mass Spectrometry, vol. 24, nᵒ 7, p. 1130-1136.

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